Processed oilseed flax fiber for use in biocomposite materials

ABSTRACT

A method and system for the production of fibers for use in biocomposites is provided that includes the ability to use both retted and unretted straw, that keeps the molecular structure of the fibers intact by subjecting the fibers to minimal stress, that maximizes the fiber&#39;s aspect ratio, that maximizes the strength of the fibers, and that minimizes time and energy inputs, along with maintaining the fibers in good condition for bonding to the polymer(s) used with the fibers to form the biocomposite material. This consequently increases the functionality of the biocomposites produced (i.e. reinforcement, sound absorption, light weight, heat capacity, etc.), increasing their marketability. Additionally, as the disclosed method does not damage the fibers, oilseed flax straw, as well as all types of fibrous materials (i.e. fiber flax, banana, jute, industrial hemp, sisal, coir) etc., can be processed in bio composite materials.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 14/530,242, filed Feb.24, 2015, which claims priority from U.S. Provisional Patent ApplicationSer. No. 61/943,740, filed on Feb. 24, 2014; U.S. Patent ApplicationSer. No. 61/948,863, filed on Mar. 6, 2014; and U.S. Patent ApplicationSer. No. 61/955,429, filed on Mar. 19, 2014, and as acontinuation-in-part of U.S. patent application Ser. No. 14/087,326,filed on Nov. 22, 2013, the entirety of which are each expresslyincorporated herein by reference.

FIELD OF THE INVENTION

The subject matter disclosed herein relates generally to biocompositematerials and, in particular, to a method and to process fibers from rawfibrous materials, such as oilseed flax, for use in the manufacture ofbiocomposite materials.

BACKGROUND OF THE INVENTION

Fibrous materials such as straw from flax, sisal, hemp, jute and coir,banana, among others, are used in the formation of biocompositematerials. Biocomposite materials utilizing these straws have enhanceddesirable properties of the biocomposite material.

However, there is a need to increase the strength of the fibers used inthe formation of these biocomposite materials, in order to createstronger, more durable biocomposites. Current flax fiber processingmethods utilize beating and grinding steps during processing, whichconsequently damages the fibers while trying to separate the shive/hurdsor other impurities from the fiber. This damage done to the straw fibersin turn decreases the strength and durability of the fibers when used toform the biocomposites that are produced with the fibers, and limits thenumber applications that the biocomposite materials can be used for as aresult.

Therefore, it is desirable to develop a method for processing fibrousmaterials, and in particular flax materials, including, but not limitedto oil seed flax, that does not damage the material thereby resulting ina fibrous material with increased strength that provides increasedproperty enhancement of a biocomposite material incorporating thefibrous material.

SUMMARY OF THE INVENTION

According to one aspect of an exemplary embodiment of the presentdisclosure, a method is provided to process a source of a fibrousmaterial without stressing and/or damaging the material to enable thematerial to retain its inherent strength when incorporated as acomponent of a biocomposite material, thereby leaving the fibers/fibrousmaterial in good condition for chemical bonding when used to form thebiocomposite material with a polymer(s). In the processing method, bothretted and unretted straw are used as sources of the fibrous materialfor the processing method.

According to another aspect of an exemplary embodiment of the presentdisclosure, the processing method utilizes a system including a tumblermachine, pressurized air, and combing process to clean the fibers in amanner to avoid physically damaging the fibers. In the process, thefibers are then subjected to roving in a carder machine, and the rivedfibers are subsequently sheared and then dried using a dehumidificationprocess.

According to still another aspect of an exemplary embodiment of thepresent disclosure, the fibrous source material used in the process is aflax, such as an oilseed flax, instead of fiber.

According to a further aspect of an exemplary embodiment of the presentdisclosure, fibers of natural plant materials are used in the fillingand reinforcement of formed biocomposite materials including the fibers.The fibers are obtained from the plant materials in a manner thatenables the fibers to be substituted for the synthetic fibers and formchemical bonds with the other biocomposite material components to atleast achieve similar mechanical characteristics for the biocompositematerial as when synthetic fibers are used, in particular the tensileand flexural strength as well as impact toughness. In addition the useof the fibers of natural plant materials do not absorb and retain water,and thus do not detrimentally affect the waterproof properties of thebiocomposite material. Further, the fibers of the natural plantcomponent do not compromise the ability of the biocomposite material tobe readily disposed of and/or recycled.

According to another aspect of an exemplary embodiment of the presentdisclosure, the natural plant fibers are mechanically treated prior tochemical treatment in order to obtain relatively pure plant material foruse in the chemical extraction process. The particular mechanicaltreatment or decortication is accomplished in a manner that reduces thebreakage of the core fibers, leaving the interior molecular structure ofthe fibers undamaged. This results in fibers that after furthertreatment can chemically bond with the components of the biocompositecomposition to provide a stronger biocomposite composition with enhancedstrength and lighter weight than other biocomposite materials.

These and other objects, advantages, and features of the invention willbecome apparent to those skilled in the art from the detaileddescription and the accompanying drawings. It should be understood,however, that the detailed description and accompanying drawings, whileindicating preferred embodiments of the present invention, are given byway of illustration and not of limitation. Many changes andmodifications may be made within the scope of the present inventionwithout departing from the spirit thereof, and the invention includesall such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings furnished herewith illustrate exemplary embodiments of thepresent invention in which the above advantages and features are clearlydisclosed as well as others which will be readily understood from thefollowing description of the illustrated embodiments.

In the drawings:

FIG. 1 is a schematic illustration of a first exemplary embodiment of anoverall fibrous material processing method performed according to thepresent disclosure;

FIG. 2 is a schematic view of an exemplary embodiment of the fiberprocessing and sorting step of the method of FIG. 1;

FIG. 3 is a schematic view of an exemplary embodiment of the fiberpreparation step of the method of FIG. 1;

FIG. 4 is a schematic view of a second exemplary embodiment of anoverall fibrous material processing method performed according to thepresent disclosure;

FIG. 5 is a schematic view of a first exemplary embodiment of acomposite material production process according to the disclosure; and

FIG. 6 is a schematic view of a second exemplary embodiment of acomposite material production process according to the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to the drawing figure in which like referencenumerals designate like parts throughout the disclosure, one exemplaryembodiment of a processing method provided for preparing various typesof fibrous materials in order for use of the fibrous material, such asoilseed flax straw, as well as all types of fibrous materials (i.e.fiber flax, banana, jute, industrial hemp, sisal, coir) etc. in abiocomposite material is illustrated generally in FIG. 1. This processis related to the processes disclosed in co-owned and co-pending U.S.patent application Ser. No. 14/087,326, filed on Nov. 22, 2013, theentirety of which is expressly incorporated by reference herein. Theseprocesses include the following, as shown in FIGS. 5-6, illustrate anexemplary process for the formation of a product 116′ created using acomposite material 102′.

The composite material 102′ is formed of a thermoplastic resin ormaterial 104′, which is the term used to denote polymer materials whichare soft or hard at the temperature of use and which have a flowtransitional range above the temperature of use. Thermoplastic resins ormaterials comprise straight or branched polymers which in principle arecapable of flow in the case of amorphous thermoplastic materials abovethe glass transition temperature (T_(g)) and in the case of (partly)crystalline thermoplastic materials above the melting temperature(T_(m)). They can be processed in the softened condition by pressing,extruding, injection molding or other shaping processes to afford shapedand molded parts. The thermoplastic material 104 used in the presentdisclosure can be any suitable thermoplastic resin material orcombination of multiple thermoplastic materials, such as a plasticincluding one or more natural or petroleum based thermoplastic resinssuch as polyethylene, polypropylene, polystyrene, polyvinyl chloride,polyacryl nitrite, polyamides, polyesters. polyacrylates and Poly LacticAcid (PLA), among others. The thermoplastic material does not have to bea homopolymer but can also be in the form of a copolymer, a polypolymer,a block polymer or a polymer modified in some other fashion.Polypropylene is a particularly useful thermoplastic material for use informing the composite material 102′ of the present disclosure.

In addition to the thermoplastic material 104′, the composite material102′ includes cellulose fibers 106′. These fibers 106′ can be obtainedfrom any suitable natural plant material 109′, such as natural fibrousplant materials including a) seed fiber plants, in particular linters,cotton, kapok and poplar down, b) bast fiber plants, in particularsclerenchyma fibers, bamboo fibers, (stinging) nettles, hemp, jute,linen or flax (fibre flax and oil seed flax), and ramie, c) hard fiberplants, in particular sisal, kenaf and manila, d) coir, and e) grasses.Bast fiber plants, such as flax and hemp, are particularly usefulnatural non-woody, plant materials from which the cellulose fibers 106′can be obtained.

The bast plants include outer bast fibers that run longitudinally alongthe length of the plants and core tissue fibers disposed within theouter bast fibers. Because the core tissue fibers are the desiredfibers, the outer bast fibers must be removed prior to use of the corefibers. In removing the outer bast fibers, care must be taken to avoiddamaging or breaking the core tissue fibers in order to maximize thelength of the core tissue fibers. Thus in a first step the straw isratter under controlled environmental conditions (e.g., field rated,chemically rated and/or water rated) followed by mechanically treatingthe bast plant materials, in which the plant materials are decorticatedby shearing the bast fibers from the core tissue fibers, as opposed tohammering or bending/flexing the plant material as in priordecortication processes. By shearing the bast fibers from the coretissue fibers, the core fibers can be kept intact more readily, therebymaintaining the overall strength and length of the core fibers. Usingthis process, core fibers of approximately 95-98% purity can beobtained. In addition, both ratted and non-ratted plant material can beused in the decortications process to obtain a clean core tissue fiberthat can be used for production of the composite material.

In each case, the core fibers of the natural fibrous plant materials109′ include cellulose, hemi-cellulose and lignin components. To obtainthe cellulose fibers 106′ utilized to form the composite material 102′from the natural plant material, the hemi-cellulose fraction 108′ andlignin fraction 110′ are separated from the cellulose fibers or fraction106′, such that a purified crystalline cellulose fraction 106′ can beadded to the thermoplastic material 104′ to form the composite material102′.

To separate the cellulose fibers/fraction 106′ from the hemi-cellulosefraction 108′ and lignin fraction 110′ of the natural plant material109′, any suitable process 111′ can be utilized, such as those employedon natural plant materials 109′ for paper pulping, e.g., soda or kraftpulping, among others. More specific examples of processes for theseparation of the hemi-cellulose fraction 108′ and lignin fraction 110′from the cellulose fibers 106′ of the plant material 109′ include thosethat utilize an alkaline material 113′, examples of which are disclosedin Hansen et al. U.S. Patent Application Publication No. 2009/0306253and Costard U.S. Patent Application Publication No. 2010/0176354, amongothers, each of which are hereby expressly incorporated by referenceherein in their entirety.

One suitable example is an alkaline separation process shown in CostardU.S. Patent Application Publication No. 2010/0176354 where a naturalplant fiber material 109′ is solubilized in an alkaline manner and whichis characterized in that the natural fiber material 109′ is treated withan alkaline material 113′ without being subjected to mechanical stressa) at a temperature of between 5 and 30° C. and then b) at a temperatureof between 80 and 150° C., and is then optionally washed and/or dried.

The alkaline materials 113′ that can be used are, among other suitablealkaline materials, alkali metal hydroxide, in particular sodiumhydroxide or potassium hydroxide, alkali metal carbonates, in particularsodium carbonate or potassium carbonate, or alkali metal phosphates, inparticular trisodium phosphate or tripotassium phosphate.

The fiber degradation takes place at a pH of approximately between 8 to14, preferably 10 to 14, more preferably 11 to 12 in the cold process(step a)) and preferably at a temperature of between 10 and 30° C.,preferably between 10 and 25° C., in particular between 15 and 25° C.,more preferably between 15 and 20° C.

The cold treatment according to step a) takes place over a period of 10minutes to 3 hours, in particular 15 minutes to 2 hours and preferably30 minutes to 1 hour.

The hot treatment used according to step b) of the natural fibermaterial also takes place between a pH of 8 to 14, preferably 10 to 14,more preferably 11 to 12, and preferably at a temperature of between 80°C. and 140° C., preferably between and 140° C., in particular between90° C. and 135° C., more preferably between 100° C. and 135° C.

The hot treatment according to step b) takes place preferably over aperiod of 20 minutes to 1.5 hours, in particular 30 minutes to 1 hourand preferably 45 minutes to 1 hour.

The concentration of alkaline material in water in steps a) and/or b)is, based on the active ingredient (typically a solid), preferably inthe range from 5 to 15 g/l, in particular 7 to 13 g/l, preferably 8 to12 g/l, particularly preferably at about 10 g/l.

The process performed according to steps a) and b) effectively dissolvesthe hemi-cellulose fraction 108′ and lignin fraction 110′ from thenatural plant material 109′, which can subsequently be removed with thealkaline solution, leaving the cellulose fraction 106′ behind forsubsequent washing and drying to a desired moisture level, e.g., about2% by weight or below.

The alkaline treatment according to the disclosure can be supported byadding excipients. Dispersants, complexers, sequestering agents and/orsurfactants are suitable here. Water glass and foam suppressors canlikewise optionally be used depending on the end-application. Othercustomary excipients can also be used. The addition of a complexer,dispersant and/or surfactant to the baths can accelerate and intensifythe wetting of the fibers. The materials customarily used for theserespective purposes in fiber treatment are suitable here.

When separated, the cellulose fibers 106′ are at least 95% w/w purecellulose fibers, i.e., the fibers 106 contain not more than about 5weight percent of material other than cellulose, i.e., lignin andhemi-cellulose. Further, the cellulose fibers 106′ have a mean fiberlength of less than about 2 mm.

Once liberated from the natural plant material 109′, the cellulosefibers 106′ can be utilized to form the composite material 102′. Thesefibers 106′ can be colored easily as the fibers 106′ are very light,i.e., almost white in color and the composite made out of these isodorless. Chemical treatment of fiber 106 affects the cellulosestructure, e.g., decreasing crystallinity and increasing the amorphousstructure. For example, the chemical treatment opens the bonds in thecellulose fraction or fibers 106 for interaction with the polymer matrix104′ in forming the composites 102′. The composite material 102′ of thepresent disclosure may mixed together and processed by extrusion,compression molding, injection molding, or any other similar, suitable,or conventional processing techniques for synthetic or naturalbiocomposites.

FIG. 5 shows one embodiment of the processing of the composite material102′ of the present disclosure. The ingredients of the compositematerial 102′, i.e., a thermoplastic material 104′ and the cellulosefibers 106′, may be blended or compounded with one another in a mannereffective for completely blending the cellulose fibers 106′ with thethermoplastic material 104′, such as in a suitable mixer, e.g., a highor low intensity mixer. Depending upon the particular composition of thethermoplastic material 104′ and the cellulose fibers 106′, thetemperature of the mixer in one embodiment should be from about 140° C.to about 220° C. for the proper combination of the components to formthe composite material. One example of a mixer effective for blendingthe fibers 106′ and thermoplastic material 104′ is a high intensitythermokinetic mixer. In these types of mixers, frictional energy heatsthe contents until they become molten, a process that takes seconds orminutes depending on the speed of the impeller. In another aspect of theinvention, heat from an external source can be supplied to melt thethermoplastic material 104′ and effect blending of the cellulose fibers106′. An example of a low intensity mixer is a ribbon blender.

The formulation of the composite material 102′ can be tailored bymodifying the amounts or ratios of the thermoplastic material 104′ andthe cellulose fibers 106′ used to form the composite material 102′depending on the particular application and/or function for thecomposite material 102′. Additives (including, but not limited to, flowenhancers, anti-oxidants, plasticizers, UV-stabilizers, foaming agents,flame retardants, etc.) are used in formulation to enhance thefunctionality of the composite product. To accommodate the particularuse and corresponding required properties of the composite material102′, the blending of the polymers/thermoplastic material 104′ and thefibers 106′ can also be varied in temperature and pressure. In addition,the blending parameters and component ratios for the composite material102′ can be altered depending upon the particular pant material fromwhich the fibers 106′ are obtained. Examples of the polymers used as thematerial 104′ include, but are not limited to acrylonitrile butadienestyrene, polyethylene, polypropylene, polystyrene, polyvinyl chloride,polyacryl nitrite, polyamides, polyesters, polyacrylates, otherengineering plastics and mixtures thereof.

In some particular embodiments of the composite material 102′, theweight ratios/percentages of the thermoplastic material 104′ and thecellulose fibers 106′ used in the formation of the composite material102′ range from 1-60%. The fiber loading in biocomposite for thefollowing process can be varied from process to process. Exemplary fiberloading percentages according to various molding processes in which thebiocomposite material 102′ is used are as follows:

-   -   a. Extrusion products: 1-30% (product examples: pipes, profiles)    -   b. Injection molding: 1-45% (product examples: small to large        components for various industries such as agricultural machinery        products, automotive interior and under hood products etc.).    -   c. Compression molding: 1-60% (product examples: kitchen        cabinets, bicycle components, interior products for agricultural        machineries (such as combine, tractor, and automotive (car, bus        etc.).    -   d. Rotational molding: 1-30% (product examples: water tanks,        large storage boxes)    -   e. Vacuuming forming/Thermoforming: 1-20% (product examples:        packaging materials, cups, plates, boxes, building insulation)

In one particular embodiment, the mixing/extruding of the thermoplasticmaterial 104′ and the cellulose fiber 106′ to form the compositematerial 102′ is performed with a dry blender, mixer, parallel screwextruder. The parallel screws in the device serve to blend the fibers106′ homogeneously with the polymer 104′, while also reducing the damageand/or breakage of the cellulose fibers 106′ in the mixture forming thecomposite material 102′. In addition, the parallel screws help to reducethe residence time of the composite material formulation 102′ byincreasing the speed of mixing of the components of the compositematerial 102′ in the device.

As a result of the use of purified cellulose fibers 106′ obtained viathe mechanical and chemical processing described previously, the fibers106′ develop a molecular bonding with the thermoplastic material 104′when blended to form the composite material 102′ which provides superiorperformance to composite materials having only mechanical bindingbetween the polymer and the reinforcing fibers. Without wishing to bebound by any particular theory, it is believed that this molecularbonding occurs as a result of the thermoplastic material 104′ flowinginto and filling the inside the modified fibers 106′ during themixing/extrusion process. The increase in the melting temperature of thebiocomposite 102′ indicates a possible polymerization effect of thefiber that diffuses or dissolves into the polymer in the composite andcorrespondingly increases the thermal resistance of composite. Due tothe porous surface of the treated fiber, molten polymer matrix enters into the porous fiber and interlocks with each other and to form a strongbinding within the biocomposite 102′. Further investigation is requiredto determine the exact nature of bond. In addition, polymer matrixesencapsulate the fiber and enhance the biocomposite strength and reducethe porosity and the formation of air pockets within the biocomposite.This molecular bonding between the fibers 106′ and the thermoplasticmaterial 104′ significantly improves the properties of the compositematerial 102′, e.g., mechanical properties including tensile andflexural strength as well as impact toughness, and thermal properties.The properties of the biocomposite 102′ vary as a result of the fiberloading and the type of polymer and/or additives used in the formationof the biocomposite 102′. This, in turn, enhances the functionality ofproducts 122′ formed of the composite material 102′ and enable theproducts 122′ to be used in a wider range of industrial applicationsthan prior fiber-reinforced materials. Also, in conjunction with thereduction in processing time in the parallel screw device, the molecularbonding between the fibers 106 and the polymer 104′ limits anysignificant reduction of inbuilt additives present inpolymer/thermoplastic material 104′. As a result, it is only necessaryto supplement any required additives, such as bonding additives, presentin the polymer 104′ during the formulation of the composite material102′, as opposed to adding the entire amount of the additives outside ofthose contained in the polymer 104′.

Once mixed/compounded, the melted composite material 102′ can be allowedto cool to room temperature and then further processed by conventionalplastic processing technologies. Typically, the cooled blend isgranulated into fine particles. The fine particles are then utilized forextrusion 112′, injection 114′ and/or compression molding to formfinished parts or products 116′.

In an alternative embodiment, the mixer can be operated without heat,such that the thermoplastic material 104′ and cellulose fibers 106′,after being mixed together, are transferred to a feed hopper, such as agravity feed hopper or a hopper with a control feed mechanism.Alternatively, the thermoplastic material 104′ and the cellulose fibers106′ can be individually fed to the extruder without being previouslymixed together. The feed hopper transfers the composite to a heatedextruder 112′.

The extruder 112′ blends the ingredients under sufficient heat andpressure. Several well-known extruders may be used in the presentinvention, e.g., a twin screw extruder. The extruder 112′ forces orinjects the composite material 102′ into a mold 114′. In an exemplaryembodiment, the flow rate of the extruder 112′ may be between about 150and 600 pounds per hour. In other embodiments, the flow rate may behigher or lower depending on the type and size of the extruder 112′. Theinjection mold 114′ may be made up of one or more plates that allow thecomposite material 102′ to bond and form a shaped-homogeneous product116′. A typical plate may be made from hardened steel material,stainless steel material or other types of metals. A cooling system(e.g., a liquid bath or spray, an air cooling system, or a cryogeniccooling system) may follow the injection mold 114′.

In the mixer, a number of optional processing aids or additives 115′ canbe added to the thermoplastic material 104 and the cellulose fibers106′. These processing aids or modifiers act to improve the dispersionof fibers 106 in the thermoplastic polymer material 104′ and also helpfurther prevent the absorption of water into the fibers 106′ and improvethe various thermal, mechanical and electrical properties of thecomposite material 102′, e.g., the strength of the resulting compositematerial 102′. The addition levels of the modifiers or compatibilizersused depends on the target properties. For example, where higher tensileand flexural strengths are desired, higher levels of modifier orcompatibilizer will be required. A compatibilizer is not required toachieve higher stiffness.

In one particular example of the present disclosure, the compositematerial 102′ includes an amount of an wear additive 115′ selected fromaluminum or copper powder, or combinations thereof to increase the wearproperties and enhance the longevity of the final product 122′.

With regard to the molding processes 120′ used to form the final product122′, the composite material 102′ improves the product 122′ formed bythese processes 120′ through the reduction of the formation of pin holesand the porosity of the material product 122′. Without wishing to bebound by any particular theory, it is believed that these results areachieved in the composite material 102′ as a result of the close packingand increased density of the fibers 106′, polymer 104′ and additives115′ due to the properties of the cellulose fibers 106′, and theconsequent removal of entrapped air bubbles during the processing of thefibers 106′ and thermoplastic material 104′, along with the additives115′, to form the composite material 102′. As a result, the finalproduct 122′ is more solid and stronger than products formed from priorfiber-reinforced materials.

Further, with the use of the cellulose fibers 106′ formed in theabove-described manner, it is possible to achieve higher gradeproperties (mechanical, thermal, electrical, etc.) for the final product122′ while using lower grade thermoplastic materials 104′ in combinationwith the cellulose fibers 106′. In particular, as a result of theproperties and purity of the cellulose fibers 106′, the fibers 106′ canbond well with a wide range of grade of polymeric/thermoplasticmaterials 104′ to achieve products 122′ with the desired properties.Further, to address any issues presented by the particularpolymer/thermoplastic material 104′, the weight percentage or weightratio of the fibers 106′ can be increased in formulation of compositematerial 104′ without compromising the quality and desired properties ofthe final product 122′. In addition, by increasing the amount of thecellulose fibers 106′ utilized in the composite material 102′, theconsequent consumption of the polymer 104′ will be reduced.

For a better understanding of the objects and advantages of the presentinvention, the same will be now described by means of several examples.However, it should be understood that the invention is not limited tosuch specific examples, but other alterations may be contemplated withinthe scope and without departing from the spirit of the invention as setforth in the appended claims.

While the formulation of the particular biocomposite material 102′depends on the final product 122′ formed from the biocomposite material102′, its functionality, and/or as described above the particularmolding process used to form the biocomposite material 102′ into thefinal product 122′.

In one example of biocomposite composition 102′, the formulationincludes:

-   -   a) natural/petroleum based thermoplastic material(s): 99-40% w/w    -   b) fiber 1-60% w/w    -   c) additives 1-5% w/w.

Biocomposite materials 102′ of different grade (e.g., extrusion grade,injection grade, compression grade, rotational grade, vacuum forminggrade) are manufactured by changing the formulation of the biocompositematerial 102′, and in one example by changing the amount of fiber 106′present and consequently adjusting the percentages of the remainingcomponents.

One particular example of a thermoforming/vacuum forming formulation forthe biocomposite material 102′ is as follows:

-   -   a) polystyrene    -   b) treated natural fiber    -   c) butane    -   d) additives (zinc stearate, magnesium stearate)    -   e) talcum powder.

Other examples of biocomposite material 102′ formed according to thepresent disclosure are found in the following tables. The properties canbe modified according to product requirement by changing/modifying theformulation

TABLE 1 Liner low density polyethylene - dicumyl peroxide pre-treatedflax fibre Flax straw/Industrial Hemp stalk Chemically Unretted Fieldretted Water retted retted Composite properties Properties Unit FlaxHemp Flax Hemp Flax Hemp Flax Hemp Melt Flow g/10 min 2.8 2.6 3.7 3.54.1 3.4 3.8 3.5 Index Melting point ° C. 130 128 129 127.4 130.1 128130.6 129 Tensile Mpa 13.2 15.3 17.6 16.9 18.3 18.7 22.2 21 StrengthTensile Impact KJ/m² 178 172 188 182 194 178 223 205 strength HardnessSD 12 11 17 18 18 17 23 21 Water % 3-5 2-6 <1 <1 <1 <1 <1 <1absorption@50 RH

TABLE 2 Liner low density polyethylene - triethoxyvinylsilanepre-treated flax fibre Flax straw/Hemp stalk Chemically Unretted Fieldretted Water retted retted Composite properties Properties Unit FlaxHemp Flax Hemp Flax Hemp Flax Hemp Melt Flow g/10 min 2.0 2.2 2.7 2.42.6 2.4 2.8 2.4 Index Melting point ° C. 129 131.2 128.6 129 129 129 129129.6 Tensile Mpa 15 14.2 18.4 17.1 20.1 17.4 19.3 17.9 Strength atYield Tensile Impact KJ/m² 178 161 188 186 199 193 218 209 strengthHardness SD 9 11 14 15 19 19 20 18 Water % 3-5 2-6 <1 <1 <1 <1 <1 <1absorption@50 RH

TABLE 3 High density polyethylene - benzoyl chloride pre-treated flaxfibre Flax straw/Hemp stalk Chemically Unretted Field retted Waterretted retted Composite properties Properties Unit Flax Hemp Flax HempFlax Hemp Flax Hemp Melt Flow g/10 min 1 1.2 1.6 1.5 1.8 1.7 1.8 1.4Index Melting point ° C. 130 128 130 130 129 130 129 130 Tensile Mpa16.3 13.7 16.3 16.2 18 18.1 23.4 19.2 Strength at Yield Tensile ImpactKJ/m² 167 157 177 179 188 185 221 178 strength Hardness SD 17 11 12 1519 22 21 19 Water % 3 2 <1 <1 <1 <1 <1 <1 absorption@50 RH

TABLE 4 High density polyethylene - dicumyl peroxide pre-treated flaxfibre Flax straw/Hemp stalk Chemically Unretted Field retted Waterretted retted Composite properties Properties Unit Flax Hemp Flax HempFlax Hemp Flax Hemp Melt Flow g/10 min 0.5 0.8 1.0 1.5 1.2 1.6 1.6 1.5Index Melting point ° C. 130 126 131.6 128.4 128 129 129 128 Tensile Mpa15 14.3 16.8 15.4 17.5 18.1 24.1 21.2 Strength at Yield Tensile ImpactKJ/m² 180 167 197 180 185 185 220 180 strength Hardness SD 13 9 14 12 1512 17 15 Water % 3 2 <1 <1 <1 <1 <1 <1 absorption@50 RH

Oilseed flax and industrial hemp fiber has promising future in theplastic industries. It is observed that unretted and chemically rettedflax and hemp can be used in plastic composite (LLDPE and HDPE).Chemically retted fiber increased the T_(m) of composite compared topure polyethylene. The increase of T_(m) may be attributed to thepolymerization effect of the fiber that diffuses or dissolves into thepolymer in composite and increased the thermal resistance of composite.This investigation indicated that chemical retting has a great influenceon mechanical properties of (flax and hemp) polymer composites productsdeveloped through rotational molding processes.

Looking now at FIG. 6, a second embodiment of the process for formingthe biocomposite material 102′ formed with a thermoplastic material 104′is shown according to the present disclosure.

Similar to the first exemplary embodiment in FIG. 5, in addition to thethermoplastic material 104′, the biocomposite material 102′ includesplant material fibers 108. These fibers 108′ can be obtained from anysuitable natural plant material 106, such as natural fibrous plantmaterials including a) seed fiber plants, in particular linters, cotton,kapok and poplar down, b) bast fiber plants, in particular sclerenchymafibers, bamboo fibers, (stinging) nettles, hemp, jute, linen or flax(fibre flax and oil seed flax), and ramie, c) hard fiber plants, inparticular sisal, kenaf and manila, d) coir, and e) grasses. Bast fiberplants, such as hemp and oil seed flax, are particularly useful naturalnon-woody, plant materials from which the fibers 108′ can be obtained.

The bast plants include outer bast fibers that run longitudinally alongthe length of the plants and core tissue fibers disposed within theouter bast fibers. Because the core tissue fibers are the desiredfibers, the outer bast fibers must be removed prior to use of the corefibers. In removing the outer bast fibers, care must be taken to avoiddamaging or breaking the core tissue fibers in order to prevent damagefrom being done to the interior molecular structure of the core fibers,as well as to maximize the length of the core tissue fibers. Thus in afirst step 210′ the plant material or straw 106′ is ratted in a storagelocation for the straw or other desired plant material under controlledenvironmental conditions (e.g., field ratted, dew ratted, chemicallyratted and/or water rated). Additionally, in an alternative embodiment,the oil seed flax or other plant material 106′ can be utilized withoutstep 110′, such that the material is unretted.

After step 210′, the plant material 106′ is cleaned in step 212′. Toclean the plant material 106′, initially the material is semi-broken instep 214′ by using a roller breaker at low rpm with little or no stressapplied to the plant material 106′. Subsequently the plant material isair and gravity cleaned in step 216′ by placing the plant material in asuitable tumbling machine (uniaxial/biaxial/multiaxial/rock and roll)with a fixed low rpm and directing a high speed air flow past and aroundthe plant material as is it tumbled in the machine. This actionseparates any loosely attached sieve and dust from the plant material106. After tumbling, in step 218′ the plant material 106′ is cleaned ina suitable cleaning device to remove the remaining sieve and dust fromthe plant material 106′. If the straw is too dirty, e.g., mud isattached to it, then it can be washed in water in between 22° C. to 50°C. and dried for further mechanical processing.

Once the straw or plant material 106′ has been cleaned, in step 220′ thebast plant materials are mechanically treated, in which the plantmaterials are decorticated to remove the bast fibers from the coretissue fibers 108′, as opposed to hammering or bending/flexing the plantmaterial as in prior art decortication processes. By decorticating thebast fibers from the core tissue fibers 108′, the core fibers 108′ canmore readily be kept intact, thereby maintaining the overall interiormolecular structure and corresponding strength intact, and maintainingan increased length of the core fibers 108′. Various processes fordecortication can be used, so long as the process places little or nostress on the core fibers 108′ so that the interior molecular structureremains undamaged, unlike other prior art processes that involvehammering or bending the plant material to remove the bast fibers. Someexamples of decortication processes that can be used in step 220′include tumbling, scutching, picking and grading the plant materials106′. Using these processes, core fibers of approximately 95-98% puritycan be obtained. In addition, both ratted and non-ratted plant material106′ can be used in the decortications process to obtain a clean coretissue fiber 108′ that can be used for production of the compositematerial.

Once removed from the bast fibers, the crude core fibers 108′ are passedthrough at least one or more, and in one embodiment, a series of five(5) machines to produce the fine, clean and uniform core fibers 108′ foruse as biocomposite reinforcement fibers. First, the crude core fibers108′ are moved in step 222′ to a combing machine in order to eliminateany remaining shive and to align the fibers into a clean fiber bundle.

In step 224′, the bundles of the clean, crude core fibers 108′ arepassed through a micro-combing process which serves to open the crudefibers and separate the individual core fibers 108′ in the bundle fromone another. In performing this individual fiber separation, the aspectratio of the individual fibers 108′ is increased to enhance thereinforcement effect of the fibers 108′ in the biocomposite. In thisstep 224′, or as a modification to step 224′, the fibers 108′ can havean antistatic lube applied thereto to enhance the separation of thefibers 108′.

In step 226′, once separated the individual fibers 108 can be processedthrough a carder to align the finer premium quality fibers (clean, long,align, more uniform, strong) while discarding the lower quality fibers.The high quality fibers 108′ are then combined in a suitable device intoa roving, or a rope-like alignment of the fiber matrix in step 228′,which is subsequently dried, by using drier such as in a dehumidifier, athin layer drier cabinet, an oven or an RF or microwave drier, amongother suitable devices to keep it dried. Drying conditions depend uponthe particular device and the drying requirement (0-6% water w/w or v/v)and RH in step 230′.

In step 232′, the roving from step 230′ is chopped or sheared into thedesired size having the highest aspect ratio (i.e., length to diameter,for example 2 mm fiber for short biocomposite) for optimum reinforcementof the biocomposite material 102′. The chopped roving can then be addedin step 234′ to the thermoplastic material 104′ in either a pre-mixedstate or directly into the hopper of an extrusion or injection moldingmachine to form the reinforced biocomposite material 102′. Thecombination or mixing of the roving with the thermoplastic material 104′in step 234′ can be accomplished by spraying the chopped fiber material108 into the thermoplastic material 104′, or by any of the manners andprocesses described previously with regard to the embodiment of FIG. 6with any of the disclosed additives, processing aids disclosed withregard to the embodiment of FIG. 6.

Two ways fiber can be processed. One without chemical treatment andother chemically treated. In both cases same mechanically fiberprocessing steps need to be followed. Prior to either the combing step222′ or the micro-combing step 224′, the core fibers 108′ of the naturalfibrous plant materials 106′ can be chemically treated as illustrated instep 225′ in order to separate the cellulose fibers 108′ from thehemi-cellulose and lignin components of the core fibers or crude fibercan be processed and later it can go for chemical treatment prior todevelop biocomposite formulation. The process employed in step 225′ issimilar to that used in step 111′ of the embodiment of FIG. 6, such thata purified crystalline cellulose fraction of fibers 108′ having anintact internal molecular structure can be added to the thermoplasticmaterial 104′ to form the composite material 102′.

Once liberated from the natural plant material 106′ in step 225′, thecellulose fibers 108′ can be further processed in either themicro-combing step 224′ or both the combing step 224′ and micro-combingstep 226′ to form fibers 108′ having the desired attributes for additionto the thermoplastic material 104′ to form the biocomposite 102′ asdescribed above.

In the illustrated embodiment of FIG. 1, the method includes an initialstep 12 of harvesting and storing the source fibrous material to beconditioned for use in the biocomposite. During storage, the fibrousmaterial is kept under controlled conditions for temperature andmoisture, among others, such as in a ventilated container or storagewarehouse (not shown) that can be maintained free from mold and mildew.

In step 14, from the storage location, the fibrous material is removedfrom the storage enclosure and processed and sorted in a number ofmethods to obtain the fibers from the fibrous material. Subsequently tothe processing and sorting of the fibrous material, in step 16 thefibers are prepared in any of a number of different processes for use asa component in the manufacture of a biocomposite material, such as thosedescribed above.

Referring now to FIG. 2, the processing and sorting step 14 initiallyincludes the various steps of cleaning the fiber in step 18, physicallyand/or chemically modifying the fiber in fiber processing step 20, anddrying the fiber in step 22, which can include the steps below alone andin conjunction with the various combinations of the process and methodsteps illustrated and disclosed regarding FIGS. 5-7.

More specifically, after separation of fiber from the straw in step 14,the crude fiber must be cleaned prior to usage in forming abiocomposite. Thus, in one exemplary embodiment of step 18, the crudefiber is put inside a rotating tumbler (not shown) including a highspeed fan (not shown) attached thereto in order to separate the unwanteddust and shive from the crude fiber. The tumbler is essentially a largemesh drum which is rotated to tumble the amount of crude fiber placedtherein while directing the air flow from the fan across the fiber toremove the shive and dust from the crude fiber by blowing the shive anddust off of the crude fiber and out of the tumbler. To clean the crudefibers, the fibers are retained in the tumbler with an air flow from thefan directed onto the fibers for between 30-60 minutes, and optionallyaround 45 minutes, to get a partially clean fiber.

From the tumbler, as a continuation of step 18 or the beginning of step20, the partially cleaned fibers then pass through a combing process ina device called a picker, as is known in the art. As the fibers passthrough the picker, the fibers are opened and separated from theincoming bunches of fibers from the tumbler into individual fibers inorder to create consistency between the fibers while also removing anyshive, hurds and dust or dirt still embedded within and/or between thefibers. From the picker, the fibers are subsequently aligned and choppedto the required size using a cutter, and, if necessary, the fibers canbe re-run through the tumbler and/or picker to further clean the fibers.

As the fibers exit the picker after being sufficiently cleaned, inpre-treatment step 20 the fibers are directed into a wet conditioningchamber (not shown) as is known in the art for physical modification,such as by washing the fiber with warm water to remove wax, pectin andany dust or muds materials attached to the fiber, or can go or bepositioned directly within a cleaning chamber (not shown) where thefibers are cleaned. Upon exiting the cleaning chamber, the fibers arechemically modified, such by placing the fibers within a device andusing a method shown in co-owned and co-pending U.S. Patent ApplicationSer. No. 61/955,429, filed on Mar. 19, 2014, the entirety of which isexpressly incorporated by reference herein, prior to drying in step 22.In this drying step 22, the cleaned and physically and chemicallymodified fibers can be placed within a suitable drying device (notshown), such as a dehumidification cabinet disclosed in co-owned andco-pending U.S. Patent Application Ser. No. 61/948,863, filed on Mar. 6,2014, and which is expressly incorporated herein by reference in itsentirety. After drying in step 22, the cleaned and dried fiber passthrough to separation step 16 in order to completely separate the fibers from one another prior to mixing with a polymer(s) to form abiocomposite formulation.

In FIG. 3, the preparation step 16, which in certain embodiments canadditionally include the physical and/or chemical modification step 20and/or the drying step 22, as well as modifications, additions orsubtractions from these steps, optionally with those steps in thedisclosure regarding FIG. 507 described above, includes the separationof the fibers in step 24 along with the conditioning of the fibers instep 26 such as by adding an anti-static agent to the fibers, thenroving, carding and/or alignment of the fibers in step 28 and thechopping and spraying of the fibers in step 30 and/or directing theformed biocomposite material with the fibers to a forming machine, suchas an extruder and/or molding machine.

Looking now at FIG. 4, in an alternative exemplary embodiment of theprocess 100, with regard to the form of the fibers as they enter theoverall process 100, there are two (2) initial states that the fibrousmaterial, e.g., flax straw, can be introduced from storage 101 to afiber breaker machine (not shown) as is known in the art for processingusing the method or process 100, namely, retted and unretted. Withretted fibrous material or straw, in step 102 the straw is initially putinto a tumbler machine, which again is a large mesh covered drum whichrotates under the control of a variable speed motor (not shown) attachedto the drum to control the rpm of the tumbler and removes shive and dustfrom the straw. In the tumbler, the straw is air and gravity cleaned bythe rotation of the straw in the drum and the direction of an air flowacross and through the straw as it is rotated by a high-speed fan (notshown) utilized in conjunction with the rotating drum. This cleaningstep 102 separates loosely attached shive from the fibers, and cleansoff any dirt and dust particles, which produces crude fibers as aresult.

With unretted straw, prior to step 102 this type of straw of fiber isplaced in a combination washing and chemical modificationmachine/chamber (not shown) such as that shown in co-owned andco-pending U.S. Patent Application Ser. No. 61/955,429, filed on Mar.19, 2014, and used in an exemplary methods shown in co-owned andco-pending U.S. patent application Ser. No. 14/087,326, filed on Nov.22, 2013, which is described above and illustrated in FIGS. 5-6, each ofwhich are expressly incorporated by reference herein in their entirety,including an amount of a suitable washing agent in step 104, and thenleft to dry in step 106, where the wet fiber is placed in adehumidification system such as that used in step 22 of the priorexemplary embodiment, where the water is removed and fiber is dried atlow temperature under a humidity-controlled environment to reduce andprevent fiber discoloration, odor, and decomposition. Once dried suchas, for example, to a moisture content of from between 8-12% weightbasis (wb) as measured by the ASAE S358.2, 1997 standard, the straw isthen placed in the tumbler in step 102 as used for cleaning the rettedstraw in step 102, where it also undergoes air and gravity cleaning in asuitable device to produce crude fibers.

Next the crude fibers are sent in step 108 through a cylindrical combingprocess/device, such as a picker, which in one embodiment includesnumerous fine metal fingers or nails extending outwardly from a rotatingdrum attached to a variable speed motor. In operation, the crude fiberpasses and is engaged by the fingers on the drum as it moves on aconveyer belt disposed adjacent the drum. The crude fibers are combedthrough by the fingers/nails to separate the fibers and removeadditional shive and dust in step 108 to completely separate the shivefrom the fiber, and to align the fibers into a clean bundle.

At this stage the fibers can be pre-treated (i.e. physically, such as bydecortications, chemically, etc.) in optional step 110, such as byplacement within the combination washing and chemical modificationmachine/chamber disclosed with respect to 20 of the previous embodimentand step 102 of this embodiment, in which the washing and chemicalmodification provided by the device protects the fiber quality whileconcurrently reducing fiber stress and fiber damage, or can be leftuntreated. In either case, the fiber bundle then undergoes a microcombing process in step 112, which is similar in form to the combingprocess of step 108, but in which the combing metal fingers are veryfine and attached to each other, to separate the individual fibers,enhancing the aspect ratio and reinforcement characteristics of theindividual fibers. At this stage the fibers can be pre-treated in anoptional step 114 in the same or in a different manner as done in step110 if the fiber has not already been pre-treated in step 110, to createa random orientation of the fibers, or can be left untreated to createan oriented long fiber composite by blending the fibers with a polymeryarn formed by the micro combing step 108.

Next the oriented individual fibers are processed through the carder instep 116, which aligns the finer, premium quality fibers to produce aroving, which is a rope-like structure, but is not twisted like a rope.The roving is subsequently sheared, such as in a cutter (not shown) asis known in the art, in step 118 to the required size in order tomaximize the aspect ratio of the fiber, thereby maximizing the strengthcharacteristics of the fibers. The sheared fibers formed in step 118 cansubsequently be used in step 122 to form the biocomposite in either apre-mixed state with the polymer(s) used to form the biocomposite, orcan be introduced into the polymer on the manufacturing line (i.e. forextrusion and injection molding) to save time and energy. However, priorto introduction into the polymer, the fiber is or may be dried in step120 through a dehumidification process, such as by placement within asuitable dehumidifying cabinet such as that discussed above with regardto step 22 of the previous embodiment, which manages the fiber qualityand has reduced energy consumption.

It should be understood that the invention is not limited in itsapplication to the details of construction and arrangements of thecomponents set forth herein. The invention is capable of otherembodiments and of being practiced or carried out in various ways.Variations and modifications of the foregoing are within the scope ofthe present invention. It also being understood that the inventiondisclosed and defined herein extends to all alternative combinations oftwo or more of the individual features mentioned or evident from thetext and/or drawings. All of these different combinations constitutevarious alternative aspects of the present invention. The embodimentsdescribed herein explain the best modes known for practicing theinvention and will enable others skilled in the art to utilize theinvention.

We claim:
 1. A biocomposite formed with fibers obtained by the methodcomprising the steps of: a) cleaning a fibrous material to separatefibers from other materials in the fibrous material by simultaneouslytumbling and directing a flow of pressurized air against the fibrousmaterial, wherein the fibers are not combed during cleaning; and b)pre-treating the fibers in a manner that places minimal stress on thefibers, wherein the step of pre-treating the fibers comprises at leastone of mechanical and chemical separation of the cellulose fiberfraction from hemi-cellulose and lignin fractions of a natural plantmaterial that does not physically damage the cellulose fibers on amacroscopic level, wherein pre-treating the fibers includes providing afirst combing process and a second combing process, and wherein thesecond combing process separates individual core fibers of each of thefibers and increases an aspect ratio of the individual core fibersenhance a reinforcing effect of the biocomposite.
 2. The biocomposite ofclam 1 wherein the fibrous materials can be retted or unretted.
 3. Thebiocomposite of claim 1 wherein the fibrous material is a flax material.4. The biocomposite of claim 1 wherein in the step of pre-treating thefibers, the step further includes treating the fibers with a chemicalduring one of a) during the second combing process, and b) immediatelyafter the second combing process, to further enhance separation of theindividual core fibers.
 5. The biocomposite of claim 4 wherein thechemical includes an antistatic lube.
 6. The biocomposite of claim 1further comprising the step of carding the fibers.
 7. The biocompositeof claim 1 further comprising the step of shearing the fibers.
 8. Abiocomposite formed with fibers obtained by the method comprising thesteps of: a) cleaning a fibrous material to separate fibers from othermaterials in the fibrous material by simultaneously tumbling anddirecting a flow of pressurized air against the fibrous material,wherein the cleaning does not damage fibers within the fibrous material,wherein the fibers are not combed during cleaning; b) pre-treating thefibers prior to at least one of a first combing process and a secondcombing process, wherein the pre-treatment does not damage the fibers;c) moving the fibers and performing the first combing process to thefibers in a manner that does not damage the fibers, and aligning thefibers into a clean fiber bundle; d) combing the clean fiber bundle viaa second combing process in a manner that does not damage the fibers,the second combing process acting to open the fibers and separateindividual core fibers from each other, which increases an aspect ratioof each of the individual core fibers to enhance a reinforcing effect ofthe individual core fibers in the biocomposite; e) carding the fibers ina manner that does not damage the fibers; and f) shearing the fibers ina manner that does not damage the fibers.
 9. The biocomposite of clam 8wherein the fibrous materials can be retted or unretted.
 10. Thebiocomposite of claim 8 wherein the fibrous material is a flax material.11. The biocomposite of claim 8 wherein in the step of combing the cleanfiber bundle via a second combing process, the step further includestreating the fibers with a chemical during one of a) during the secondcombing process, and b) immediately after the second combing process, tofurther enhance separation of the individual core fibers.
 12. Thebiocomposite of claim 11 wherein the chemical includes an antistaticlube.